Method and apparatus for using wire strands as fourdrinier wire drainage elements

ABSTRACT

IN A FOURDRINIER PAPERMAKING MACHINE, PAPER STOCK CONSISTING OF APPROXIMATELY 99 PERCENT WATER IS FLOWED ONTO AN ENDLESS MOVING WIRE MESH, AS THIS WATER SEEPS THROUGH THE WIRE MESH AND FORMS AN IRREGULARLY SHAPED FILM ON ITS UNDERSIDE, THE SURFACE TENSION OF THE FILM IS BROKEN AND THE WATER DRAINED BY A SERIES OF TENSIONED WIRE STRANDS DISPOSED BELOW THE MESH AND TRANVERSELY TO MESH FLOW. THE WIRE STRANDS ARE SECURED AT EACH END TO THE MACHINE FRAMES BY ADJUSTABLE WIRE BRACKETS, WHICH PROVIDE VERTICAL ADJUSTMENT TO REGULATE THE DISTANCE BETWEEN THE WIRE MESH AND THE WIRE STRANDS AND PARALLEL ADJUSTMENT TO ALIGN THE WIRE STRANDS PARALLEL TO THE WIRE MESH. MEANS ARE ALSO PROVIDED FOR TENSIONING THE WIRE STRANDS.

April 1971 R. E. TAYLOR,- JR 3,574,054

METHOD AND APPARATUS FOR USING WIRE STRANDS AS FOURDRINIER WIRE DRAINAGE ELEMENTS Filed Aug. 6, 1968 2 Sheets-Sheet l as g p 1971 R. E. TAYLOR. JR

METHOD AND APPARATUS FOR USING WIRE STRANDS AS FOURDRINIER WIRE DRAINAGE ELEMEN 2 Sheets-Sheet :3

Filed Aug.

United States Patent O US. Cl. 162-211 Claims ABSTRACT OF THE DISCLOSURE In a Fourdrinier papermaking machine, paper stock consisting of approximately 99 percent water is flowed onto an endless moving wire mesh. As this water seeps through the wire mesh and forms an irregularly shaped film on its underside, the surface tension of the film is broken and the water drained by a series of tensioned wire strands disposed below the mesh and transversely to mesh flow. The wire strands are secured at each end to the machine frames by adjustable wire brackets, which provide vertical adjustment to regulate the distance between the wire mesh and the wire strands and parallel adjustment to align the wire strands parallel to the wire mesh. Means are also provided for tensioning the wire strands.

BACKGROUND OF THE INVENTION The field of this invention is the drainage of water from paper stock as it is carried on the endless wire mesh of a Fourdrinier papermaking machine. The stock, as initially flowed onto the wire mesh, generally consists of approximately 99 percent water so that the stock fibers are kept in suspension. This suspension affords time for the fibers to interweave and produce a well formed sheet. Most of this water must be subsequently drained from the stock before it reaches the first press. Approximately 60 percent of this water must be drained gradually over the initial mesh flow so that the fibers are given enough suspension time to form properly. Most of the remaining water is rapidly drained by suction boxes. The strength of the paper product is increased when this drainage is accomplished efficiently and uniformly.

The most common means for drainage in the prior art is to pass the wire mesh over a series of table rolls and/ or foils. The efficiency of table rolls is hindered by the tendency of the rolls to throw water back on the underside of the wire mesh at high operating speeds. To counteract this tendency, baffles or drainage blades have been placed between the rolls to prevent the rolls from throwing back water. The rolls can even be eliminated and drainage can be accomplished solely with drainage blades or foils. (Cf.: Wagenknecht US. Pat. No. 2,744,454; Petruscke, Increased Drainage Steps Up Wet End Speed, Pulp & Paper, Oct. 16, 1967, p. 29 et seq.) Huyck Hydrofoils, produced by Formex Co., Greenville, Tenn, and Johnson Foils, produced by Johnson Foils, Inc., of Springfield, Mass. are examples of such foils presently in use.

A shortcoming of rolls and foils is that they are costly to produce. This is especially true of foils because of the costly precision machining and stressing necessary for their production. A related disadvantage of these devices is that their size creates a physical limitation on the number which can be placed under the mesh in any given installation.

A further common shortcoming of existing devices is that, when the suction caused by the movement of the wire mesh and the drainage device immediately following the separation of the mesh from the drainage device is released, upward splashings of the paper stock (kick ice ups) result. These kick ups cause disturbances in the web and hinder paper formation. Foils tend to reduce the severity of these kick ups but do not completely eliminate them. The patent to Lee, No. 3,332,838 discloses means for reducing kick-up effects of table rolls.

SUMMARY OF THE INVENTION In accordance with applicants invention, the wire mesh of a Fourdrinier papermaking machine is passed over a plurality of tensioned wire strands disposed transversely to mesh flow. The wire strands are positioned and secured by support brackets at each end which are secured to the machine frame by an adjustable frame attachment bracket. The wire support brackets can be vertically adjusted to achieve the desired spacing between the wire strands and the underside of the wire mesh by a vertical adjusting means and the alignment of the wire strands can be adjusted so that they are in a plane parallel to a plane formed by the mesh underside by an alignment adjusting means. The support bracket is provided with an aligning plate to insure that the wire bracket is maintained parallel to the machine frame and tension is produced in the wire strands by tightening a tension screw against the machine frame. Thus the set of drainage wire strands can be accurately positioned within the zone where surface tension holds the water to the underside of the mesh but without touching the mesh in the average or normal position of the relatively moving mesh and wire strands.

This novel improvement in paper web drainage apparatus significantly reduces the cost of papermaking machinery because it utilizes no large or costly machined metal parts.

This invention also eliminates kick up disturbances in the web as the stock passes over the drainage wires because the wire strands do not contact the mesh and hence no suction discontinuity is produced. This results in smoother web travel and somewhat increases the strength of the paper.

A related advantage of the present invention is that the small diameter of the drainage wire strands enables them to be placed at closer intervals along the flow-line of the mesh. This produces more gradual and uniform drainage which results in a stronger product.

Accordingly, it is a general object of this invention to provide a device which reduces the cost of Fourdrinier paper machinery drainage apparatus.

It is another object of this invention to provide a method and apparatus to efiiciently dewater a paper stock web without creating vertical disturbances in that web.

It is a further object of this invention to provide a method and apparatus to drain a paper stock web on a Fourdrinier wire mesh gradually and uniformly along its flow path and with improved effectiveness.

DESCRIPTION OF THE DRAWINGS Other objects and features and many of the attendant advantages of the present invention will become more apparent as reference is bad to the following detailed description when considered together with the-accompanying drawings wherein:

FIG. 1 is a diagrammatic side elevation view showing the breast roll, side frame support, two drainage wire strand assemblies and a table roll as related to the Fourdrinier wire mesh;

FIG. 2 is a perspective plan view of the drainage wire strand assembly;

FIG. 3 is a side elevational view of the assembly of FIG. 2 partially broken away and in cross-section; and

FIG. 4 is a top elevational view of the bracket of FIG. 2 partially broken away and in cross-section.

The operational environment of this invention is set forth in FIG. 1. Paper stock is flowed onto an endless Fourdrinier wire mesh 2 at headbox 4. The mesh 2 is supported and driven by a breast roll 6 at the headbox end and a similar roll (not shown) at its downstream end. Mesh 2 is supported in its flow path by one or more table rolls 8. The drainage wire strand assemblies of the present invention, indicated generally by reference numeral 10, two of which are shown here, are attached to side frame support 12 of the papermachine and are adjusted so that the drainage wires 14 are positioned slightly below and parallel to the underside of mesh 2.

The structure of the preferred embodiment of this invention is set forth in greater detail in FIG. 2. Tensioned drainage wire strands 14 are positioned and secured by an adjustable wire bracket 16. The bracket 16 is attached to a swivel adjusting head assembly 1 8 by a pivot pin 20 and is provided with a slot 17 to receive a parallel adjustment screw 26. The swivel adjusting head 18 is provided with an antiswivel plate 22 on side 19, a parallel adjustment screw bracket 24, threaded to receive a parallel adjusting screw 26 and a receiving cavity 28 (shown in FIG. 3) for vertical adjustment screw 30. Vertical adjustment screw 30 is in threaded engagement with and passes through bracket positioning block 32 via a threaded, vertical and centered vertical screw hole 31 in block 32. Bracket positioning block 32 is fixedly attached to and positioned between lateral slides 34. A mounting support block 36 is positioned between and in slidable contact with lateral slides 34. The mounting block 36 is also provided with a vertical threaded and centered frame bolt hole 38 and a tension bolt receiving cavity 40 (shown in FIG. 4).

The ends of lateral slides 34 which are remote from positioning block 32 are secured to a bar 42 which is in threaded engagement with a tensioning bolt 44 which passes through a centered threaded and horizontal tension bolt hole 43. The external end of tension bolt 44 is provided with a tightening handle 47. The internal end of the tension bolt 44 has an enlarged head 46 rotatably retained within the mounting block 36. (See FIG. 4.)

Referring now to FIG. 3, drainage wire strands 14 are passed through spaced wire holes 48 in the bracket 16 and secured by set screws threaded into set screw holes 50. Tongue 54 of swivel adjustment head 18 is inserted in slot 17 and pivot pin 20 is passed through pivot receiving holes 52 and 56 and retained by a cotter pin 58.

Anti-swivel plate 22 is secured as by welding to the internal side 19 of swivel adjusting head 18. Side 19 and internal side 60 of the block 32 are parallel to the axis of the vertical adjustment screw 30 so that plate 22 rests flush on surface 60 to maintain alignment of the bracket 16.

The receiving cavity 28 is a cylindrical hole with a dimension slightly larger than reduced diameter end 62 of vertical adjusting screw 30. The swivel 18 is also provided with a locking pin hole 64, the axis of which is tangential to cavity 28. The bolt end 62 is provided with a circumferential rounded groove 63, the diameter of which is slightly larger than that of locking pin 65. In practice a locking pin 65 is passed through aperture 66 in antiswivel plate 22 and locking pin hole 64 and secured by a cotter pin or similar means to retain the swivel head 18 to the bolt end 62.

The threaded portion of vertical adjustment screw 30 passes through threaded aperture 31 in the block 32 and the lower end is provided with an aperture 68 through which a handle can be inserted.

Referring now to FIG. 4, mounting support bracket 36 is shown positioned by and in slidable contact with lateral slides 34 along grooves 35. The frame bolt hole 38 is threaded through bracket 36 and centered on the axis of tension bolt 44. Tension bolt receiving cavity 40 is a keyshaped cavity of sufiicient size to hold support bracket engagement means 46. Tension plate 42 is positively secured to the external ends of lateral slides 34 by screws or 4 similar means. The external end of the bolt 44 is provided with handle 47.

In practice, two drainage wire strand assemblies 10 are attached to opposite Fourdrinier machine frame supports 12 to support each set of drainage wire strands. Each assembly is aifixed to the frame 12 by passing a bolt through frame 12 and frame bolt hole 38 in mounting bracket 36. The assemblies 10 can be supported either above or below frame 12 to suit the machine and assembly 10 dimensions.

The drainage wire strands 14 are mounted in wire bracket 16 by passing them through wire holes 48 and securing them by driving set screws through set screw holes 50. The length of wire strands 14 should be uniform and should be such that, when tensioned, wire brackets 16 are positioned slightly inside the outer edge of mesh 2 to avoid the possibility that distortion of the mesh 2 at its edges would damage the wire strands 14. It has been found that a inch diameter, nylon coated, stainless steel cable is a suitable material for wire strands 14, although various other sizes and materials are satisfactory.

Drainage wire strands 14 should be positioned slightly below, and in a plane parallel to, a plane formed by the underside of mesh 2. The vertical adjustment is accomplished by rotating vertical adjustment screw 30 in the threaded hole 31 in block 32. Any axial movement in the screw 30 relative to block 32 is transmitted to swivel adjusting head 18, and hence to wire bracket 16', by the interaction of the receiving cavity 28, locking end 62, looking groove 63 and a locking pin 65.

The parallel adjustment is accomplished by interaction of pivot pin 20 and parallel adjusting screw 26. Since wire strands 14 are tensioned, they produce a downward force on bracket 16. The otfcenter positioning of pivot 20 and the location of parallel adjusting screw 26 on the opposite side of the vertical center line of said bracket provide a positive means of adjusting the horizontal alignment of bracket 16. Parallel alignment with the underside of mesh 2 is necessary to insure that all wires 14 are equidistant from mesh 2 so that drainage is uniform and efficient.

Wire strands 14 are tensioned by tightening tension bolt 44 with handle 47. This tightening draws tension plate 42 towards the handle end of bolt 44 because cavity 40 and engagement means 46 enable bolt 44 to rotate but prevent axial movement. Since plate 42 is secured to lateral slides 34 with stud bolts or similar means, and since positioning block 32 is positively attached to the internal end of slides 34, wire bracket 16 is also drawn in the external direction and wire strands 14 are tensioned. Wire bracket 16 is maintained in a position parallel to side frame supports 12 by anti-swivel plate 22.

All parts of this assembly 10, (with the exception of the coating material for wires 14 described above) should be made of non-water corrosive metal. In practice, it has been found that brass is an acceptable material for wire bracket 16, swivel head bracket 18, anti-swivel bar 22, and parallel screw positioning means 24, while stainless steel is an acceptable material for the remaining elements.

As the paper stock travels on mesh 2, the water contained therein seeps through mesh 2 by force of gravity and forms water globules of varying dimensions held together under the mesh by the surface tension of the water. Absent any drainage means, these globules burst when their weight becomes large enough to overcome the surface tension which holds them to the mesh. The present invention facilitates drainage by breaking the surface tension with drainage wire strands 14 positioned a short distance under mesh 2. The constant surface tension breakage allows more water to drain because water is being constantly expelled from the underside to make way for more to enter. Thus, the inertia in water flow inherent in unaided drainage caused by the necessity of waiting until the weight of the water accumulated on the underside is great enough to break its surface tension is eliminated by the present invention. It has been found that a set of six (6) drainage wire strands v14 at threefourths inch intervals drains at least as much water as a standard table roll 8. It has accordingly been found that the utilization of this invention reduces the number of table rolls 8 needed to the minimum number required for support of mesh 2, and thus, significantly reduces equipment costs.

A further feature of this invention is that wire strands 14 do not contact mesh 2 so that mesh wear is reduced. More importantly, this feature eliminates some of the shortcomings inherent in the use of rolls and foils for drainage. Since these prior art elements contact mesh 2, they remove water by scraping it off the underside of mesh 2 and create a suction which causes the stock to jump at each point of contact. The present invention does not use suction to eflFect drainage and thus eliminates kick up disturbances in the stock, thereby causing the paper produced to be smoother. An associated advantage of this invention is that no special apparatus is needed to insure that the suction is uniformly broken to avoid streaking.

The small size of wire strands 14 enables a plurality of them to be positioned in a space normally occupied by a roll or a foil and, therefore, gives greater flexibility in the choice of drainage rate.

There are obviously many modifications and variations of the present invention possible in light of the above teachings which would not depart from the spirit and scope of the invention. It is to be understood, therefore, that the invention is not limited in its application to the details of structure specifically described or illustrated and that within the scope of the appended claims, it may be practiced otherwise than as specifically described or illustrated.

I claim:

1. A method for draining the film or accumulation of water from the underside of the moving wire mesh of a Fourdrinier papermaking machine, said method comprising positioning and supporting a plurality of substantially parallel drainage wire strand transversely to, at a predetermined distance from, and substantially uniformly spaced from the underside of said 'Wire mesh in the zone where said film or accumulation are held to said mesh by surface tension.

2. A drainage apparatus for removing the film or accumulation of fluid forming on the underside of a permeable mass of fluid-containing material, said apparatus comprising: a drainage wire strand positioned at a predetermined distance below and substantially uniformly spaced from said underside of said permeable mass, said member being within the zone where said film and accumulation of fluid are held to said mass by surface tension; and means for creating relative motion between said mass and said strand transverse to said strand.

3. A drainage apparatus for the moving wire mesh of a Fourdrinier papermaking machine comprising: at least one drainage wire strand disposed transversely beneath said wire mesh; means for tensioning said wire strand; and means for positioning and supporting said wire strand in spaced relation to the under surface of said mesh within the zone where water passing through the mesh is held by surface tension.

4. The drainage apparatus as set forth in claim 3 in which said wire strand positioning and supporting means comprises: means including drainage wire brackets disposed transversely to the mesh wire movement, said brackets provided with means to receive and secure a plurality of substantially parallel drainage wire strands.

5. The drainage apparatus as set forth in claim 4 in which each said wire positioning and supporting means includes means for adjusting the vertical positioning of said drainage wire brackets.

6. The drainage apparatus as set forth in claim 5 in which said vertical adjusting means comprises: a threaded vertical adjustment screw provided at one end with an aperture and with a locking means and a handle at its other end, an adjustment head assembly connected to said bracket, a receiving cavity in said head assembly for said one end of said adjustment head assembly, a locking rod hole provided in said adjustment head assembly, a locking rod positioned in said rod hole and said aperture for locking said screw with said adjustment head assembly, and a positioning block secured in a fixed vertical position which is provided with a threaded vertical screw hole through which said screw is rotatable for vertically positioning said adjustment head assembly and said wire bracket.

7. The drainage apparatus as set forth in claim 6 in which each said wire bracket is provided with means for adjusting the horizontal alignment of said wire bracket.

8. The drainage apparatus as set forth in claim 7 in which said horizontal alignment means comprises: an oif-centered pivot connecting each said wire bracket and said adjustment head; and an opposed parallel alignment screw on the opposite side of the vertical center line of each said bracket for adjusting the horizontal alignment of each said bracket with said adjustment head assembly.

9. The drainage apparatus as set forth in claim 8 in which each said adjustable head assembly is provided with an anti-swivel plate which maintains alignment of said adjustment head assembly and said bracket to the Fourdrinier machine frame to which said positioning and supporting means is attached.

10. The drainage apparatus as set forth in claim 3 in which said wire strand tensioning means comprises: a mounting support bracket affixed to the side frame supports of a Fourdrinier paper making machine, said bracket being between and in lateral slidable contact with lateral sides connected to said frame supports, said bracket provided with a tension bolt receiving cavity; a positioning block secured to and between the internal ends of said lateral slides; a tension plate secured to and between the external ends of said lateral slides, said tension plate having a threaded tension bolt hole; and a tension bolt threaded through said tension plate and provided with support bracket engagement means at one end, said engagement means being rotatably retained in said receiving cavity; and a handle connected to the other end of said tension bolt, said positioning block being secured to said wire supporting and positioning means.

US. Cl. X.R.

22 g UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3.574.054 Dated April 6 1971 Inventor(s) Ruel E. Taylor. Jr.

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 5, line 40, "strand" should read "strands",

line 51, "member" should read "strand".

Signed and sealed this 28th day of December 1971.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Acting Commissioner of Pater 

